It is known to implant inflatable prostheses in the periurethral tissues of a patient to provide support to the urethral sphincter as a treatment for urinary incontinence. Such implants are described, for example, in U.S. Pat. No. 4,832,680 to Haber et al. The prostheses, similar to tiny balloons, are introduced into the periurethral tissues and positioned, one on either side of the urethra, in an uninflated condition. The prostheses are then inflated by infusing saline solution through a cannula. As the prostheses expand they exert pressure and cause coaptation of the urethra.
The inflatable prostheses normally used for this procedure comprise a balloon mounted around a main body and anchored to the body at its rearward end. As the balloon is inflated, the major direction of elongation is longitudinal, that is, parallel to the urethra. Thus if the prostheses are not positioned closely enough to the urethra, or if the periurethral tissues tend to be inelastic, as in the case of scar tissue from previous surgery or radiation treatment, considerable additional inflation of the prostheses is required to result in relatively minor increases in coaptative pressure.
Inflatable prostheses are known which expand primarily in a radial direction. Such prostheses are disclosed, for example, in U.S. Pat. No. 3,834,394 to Hunter et al. These prostheses comprise a balloon whose opposite ends are linked to prevent axial elongation. As the balloon is first inflated, the only possible direction of expansion is radially. The inflatable prosthesis of the aforementioned U.S. Pat. No. 3,834,394 is disclosed only with respect to vascular applications. Furthermore, even though such a prosthesis might provide advantages in terms of enhanced lateral pressure, the pressure tends to be exerted at only a single point.
Thus there is a need for an improved inflatable prosthesis which when positioned within the periurethral tissues will exert radial pressure against the urethra but which will exert that pressure along a substantial length of the urethra.
Them is a further need for an inflatable prosthesis for implanting in periurethral tissues which will expand in such a way as to provide a greater margin of error with respect to placement of the devices.
Them is also a need for an inflatable implant which expands primarily radially but which exhibits some limited degree of longitudinal expansion.